Various types of devices have been developed for implantation into the human body to provide various types of health-related therapies and/or monitoring. Examples of such devices, generally known as implantable medical devices (IMDs), include cardiac pacemakers, cardioverter/defibrillators, cardiomyostimulators, various physiological stimulators including nerve, muscle, and deep brain stimulators, various types of physiological monitors, and drug delivery systems, just to name a few. For purposes of this application, reference will be made only to implantable cardiac devices and particularly to implantable cardiac pacemakers and defibrillators, it being understood that the principles herein may have applicability to other implantable medical devices as well.
An implantable medical device (IMD) may be a device such as an implantable pulse generator (IPG), commonly referred to as a pacemaker, which is used to stimulate the heart into a contraction if the sinus node of the heart is not properly timing, or pacing, the contractions of the heart. Modern cardiac devices also perform many other functions beyond that of pacing. For example, some cardiac devices such as implantable cardioverter defibrillators (ICD) may also perform therapies such as defibrillation and cardioversion as well as provide several different pacing therapies, depending upon the needs of the user or patient and the physiologic condition of the patient's heart. For convenience, all types of implantable medical devices will be referred to herein as IMDs, it being understood that the term, unless otherwise indicated, is inclusive of an implantable device capable of administering any of a number of therapies to the heart of the patient.
In typical use, an IMD is implanted in a convenient location usually under the skin of the patient and in the vicinity of the one or more major arteries or veins. One or more electrical leads connected to the IMD are inserted into or on the heart of the user, usually through a convenient vein or artery. The ends of the leads are placed in contact with the walls or surface of one or more chambers of the heart, depending upon the particular therapies deemed appropriate for the patient.
One or more of the leads is adapted to carry a current from the IMD to the heart tissue to stimulate the heart in one of several ways, again depending upon the particular therapy being delivered. The leads are simultaneously used for sensing the physiologic signals provided by the heart to determine when to deliver a therapeutic pulse to the heart, and the nature of the pulse, e.g., a pacing pulse or a defibrillation shock. Recently, bipolar and multi-polar permanently implantable pacing leads and leads for use in pacing and cardioversion/defibrillation (collectively referred to as permanent implantable cardiac leads) have been developed using coaxially arranged, coiled wire conductors and/or parallel-wound, multi-filar coiled wire conductors and having proximal lead connector assemblies coupled thereto. The proximal lead connector assemblies are formed with a proximal lead connector pin and one or more distally located ring-shaped conductive elements or lead connector rings.
The proximal lead connector assembly is inserted into the IMD so that the lead connector pin electrically contacts a connector located on a connector section affixed to the IMD. The connector section typically includes a bore containing an electrical connector that is configured to engage with a connector pin located on the proximal lead connector assembly. In addition, the connector section may comprise conductive contacts configured to contact the lead connector rings of the proximal lead connector assembly. As IMD technology progresses, the size of IMDs and associated components become increasingly reduced in size. Consequently, more conductive contacts are placed closer together in a smaller space of the connector bore. Typically, sealing rings have been used to isolate electrical contacts from one another. In addition, the sealing rings prevent fluid from entering the connector bore. However, because of the reduced IMD size, and thus, reduced sealing ring size and increased number of sealing rings employed, it has been found that, at times, when a connector end assembly is inserted into the connector section, increased insertion force is needed to press the lead connector assembly into the IMD. Similarly, increased withdrawal force is needed to remove the lead connector assembly from the connector bore.
Accordingly, it is desirable to provide an IMD with a fluid seal that permits a proximal lead connector assembly to be inserted into the connector section of the IMD with reduced insertion force. In addition, it is desirable to provide an IMD with a fluid seal that permits the proximal lead connector assembly to be withdrawn from the connector section of the IMD with reduced withdrawal force. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.